A low-k dielectric sacrificial material is formed within a microelectronic structure covered with a layer defining an exhaust vent. At an appropriate time, the underlying sacrificial material is decomposed and exhausted away through the exhaust vent. Residue from the exhausted sacrificial material accumulates at the vent location during exhaustion until the vent is substantially occluded. As a result, an air gap is created having desirable characteristics as a dielectric.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method comprising: forming a cavity between a plurality of dielectric layers by thermally decomposing a sacrificial dielectric material through an exhaust vent in one of the dielectric layers; and substantially isolating the cavity by at least partially occluding the exhaust vent by accumulating a residue from the sacrificial dielectric material thermal decomposition.
2. The method of claim 1 wherein thermally decomposing the sacrificial dielectric material further comprises heating the dielectric material beyond its thermal decomposition temperature.
3. The method of claim 1 further comprising cooling the dielectric layers.
4. The method of claim 1 wherein thermally decomposing the sacrificial dielectric material further comprises exposing the sacrificial dielectric material to a carrier plasma.
5. The method of claim 4 further comprising dry etching a portion of the sacrificial dielectric material to improve reactivity with the carrier plasma.
6. The method of claim 4 wherein the carrier plasma includes a gas selected from the group consisting of oxygen, hydrogen, and nitrogen.
7. The method of claim 1 wherein the residue plugs the exhaust vent.
8. The method of claim 1 wherein the sacrificial dielectric material is an organic polymer.
9. The method of claim 8 wherein the organic polymer is selected from the group consisting of polynorbomene, cross-linked photoresist, photosensitive polyimide, polyarylene, and poly(aryl ether).
10. The method of claim 1 wherein the dielectric layer including the exhaust vent is a ceramic material.
11. The method of claim 10 wherein the dielectric layer including the exhaust vent is a material selected from the group consisting of silicon nitride, silicon carbide, silicon dioxide, carbon doped oxide, and aluminosilicate.
12. The method of claim 1 wherein the residue is the same material as the sacrificial dielectric material.
13. The method of claim 1 wherein accumulating said residue from the sacrificial dielectric material thermal decomposition further comprises depositing a layer of residue on the walls of said cavity.
14. The method of claim 1 wherein thermally decomposing said sacrificial dielectric material comprises retaining at least a portion of said sacrificial dielectric material.
15. A method comprising: forming a cavity above a first dielectric layer and below a second dielectric layer by thermally decomposing a sacrificial dielectric material through an exhaust vent in said second dielectric layer, wherein said first dielectric layer acts as an etch stop during the formation of said cavity; and substantially isolating said cavity by at least partially occluding said exhaust vent by accumulating a residue formed from thermally decomposing said sacrificial dielectric material.
16. The method of claim 15 wherein thermally decomposing said sacrificial dielectric material comprises exposing said sacrificial dielectric material to a carrier plasma.
17. The method of claim 16 further comprising dry etching a portion of said sacrificial dielectric material to improve reactivity with said carrier plasma.
18. The method of claim 15 wherein said residue plugs said exhaust vent.
19. The method of claim 15 wherein said sacrificial dielectric material is an organic polymer.
20. The method of claim 15 wherein thermally decomposing said sacrificial dielectric material comprises retaining at least a portion of said sacrificial dielectric material.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 10, 2004
February 19, 2008
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